Micb 202: Bacterial Disease Xii - Intracellular Existence

Front 1

What are the two categories of intracellular parasite?

Back 1

facultative and obligate

Front 2

Give an example of a facultative intracellular parasite

Back 2

Salmonella species

Front 3

Give an example of an obligate intracellular parasite

Back 3

Chlamydia species

Front 4

Salmonella is extracellular (T/F)

Back 4

F. It is intracellular.

Front 5

Describe Salmonella morphology

Back 5

Gram(-)
flagellated
facultatively anaerobic
bacilli

Front 6

What are Salmonella's three major antigens?

Back 6

H (flagellar) antigen
O (somatic) antigen
K (capsular) antigen

Front 7

What shape are bacilli? Cocci?

Back 7

rod-shaped. spherical.

Front 8

How is salmonella transmitted?

Back 8

via feces of infected people or animals via contaminated food or drink

Front 9

What are the two main diseases associated with Salmonella?

Back 9

salmonellosis and typhoid fever

Front 10

Vi is possessed primarily by the Salmonella serovars that cause ___

Back 10

typhoid fever

Front 11

What is the naming system for Salmonella?

Back 11

Salmonella (genus) + species (enterica or bongori) + serovar_type

Front 12

What are the two species of Salmonella?

Back 12

enterica, bongori

Front 13

Where does Salmonella diversity stem from?

Back 13

an ability to create variation in the H, K, and O antigens

Front 14

What do serological identification methods use?

Back 14

They employ antibodies

Front 15

What are the three serological identification methods?

Back 15

agglutination tests, ELISAs and Western blots

Front 16

Define serovars

Back 16

strains differentiated by serological means

Front 17

Define biovars

Back 17

strains differentiated by biochemical or other non-serological means

Front 18

What are the five Salmonella virulence factors?

Back 18

-adhesins
-LPS
-capsules
-two type III secretion systems
-ability to invade and replicate in host cell

Front 19

Define pathogenicity island

Back 19

large region of DNA encoding clusters of genes associated with virulence

Front 20

SPI_ contains a group of genes called ___ genes responsible for membrane ruffling assoc with invasion of host cell by Salmonella

Back 20

SPI1, inv

Front 21

What are the three main serovars of Salmonella enterica?

Back 21

Typhi
Typhimurium
Enteritidis

Front 22

What are the two most common serovars for infection in the US?

Back 22

Typhimurium
Enteritidis

Front 23

Salmonella are very ___ sensitive

Back 23

acid

Front 24

Which Salmonella is one of the causative agents of typhoid fever?

Back 24

Salmonella enterica serovar Typhi

Front 25

What is the host range of S. typhi?

Back 25

humans only

Front 26

What is the incubation period of typhoid fever?

Back 26

week to a month after ingestion

Front 27

Where does S. typhi multiply once eaten?

Back 27

spleen and liver

Front 28

Does S. typhi get released into bloodstream?

Back 28

Y

Front 29

In what organ does S. typhi persist in chronic carriers?

Back 29

in the gall bladder

Front 30

What Salmonella produces a typhoid-like fever in mice, and a self-limiting gastroenteritis in humans?

Back 30

S. typhimurium

Front 31

When can S. typhimurium be dangerous to humans?

Back 31

immunocompromised individuals. bacteria may enter bloodstream

Front 32

What is the difference between food infection and food poisoning?

Back 32

food infection = bacteria in food that multiply in gut causing delay in symptom onset

food poisoning = toxins in food (not necessarily any live bacteria)

Front 33

How does S. typhimurium enter the host in the mouse model?

Back 33

through 'M' cells = specialized intestinal tract cells that sample antigens from the lumen of the intestine

they translocate and are eaten by macrophages associated with Peyer's patches

Front 34

S. typhimurium produces harmful enterotoxins (T/F)

Back 34

F

Front 35

What is the function of the S. typhimurium type III secretion system?

Back 35

to inject proteins into the intestinal cell

Front 36

What do the injected proteins of S. typhimurium do?

Back 36

promote internalization of the bacteria

Front 37

How does the infected host cell respond to the injected proteins of S. typhimurium?

Back 37

produces inflammatory agents attracting neutrophils

the neutrophils will then produce prostaglandin

Front 38

What is the role of the host neutrophils during S. typhimurium infection?

Back 38

produce prostaglandin after migrating to site of infection

Front 39

What is the effect of prostaglandin on intestinal epithelial cells?

Back 39

increases the internal concentration of cAMP

Front 40

What do increased levels of cAMP cause?

Back 40

inhibition in Na+ uptake, and increase in Cl- secretion

Front 41

What are Type III secretion systems?

Back 41

multi-protein assemblies essential to virulence of Gram(-) bacteria, which inject virulence factors into eukaryotic host cells

Front 42

Type III secretion systems are assocaited with Gram(+) bacteria (T/F)

Back 42

F. Gram(-) bacteria.

Front 43

How is the serotype identified during diagnosis?

Back 43

antigenic analysis of O (cell wall antigen) and H (flagellar antigen) using polyvalent specific antisera

Front 44

Salmonella entering bloodstream is common (T/F)

Back 44

F

Front 45

type I fimbriae and plasmid-encoded fimbriae are examples of ___

Back 45

adhesins used by Salmonella

Front 46

During invasion by Salmonella, what triggers the "ruffling"?

Back 46

actin rearrangements, mediated by the Salmonella SPI1 system

Front 47

What pathogenicity island is the Type III injector system on?

Back 47

SPI2

Front 48

What is the function of the proteins that Salmonella injects into endosomes?

Back 48

alters the structure so that they can no longer fuse with lysosomes

Front 49

How does Salmonella escape destruction inside the host cell?

Back 49

It modifies an endosome to prevent lysosome fusion then divides inside of it

Front 50

Salmonella mutants lacking the SPI2 island are still virulent (T/F)

Back 50

F

Front 51

S. ___ and S. ___ are usually resolved within a week and do not require treatment

Back 51

typhimurium, enteritidis

Front 52

Which antibiotics are the treatment of choice for S. typhi infections?

Back 52

chloramphenicol
ceftriaxone

Front 53

For which serovars of Salmonella has a vaccine been made?

Back 53

S. typhi only
2 are injected dead bacteria
1 is oral live attenuated

Front 54

What are the two types of cell-mediated response?

Back 54

T-cell effector mechanisms

activation of macrophages

Front 55

SPI_ is responsible for mediating actin rearrangements "ruffling" at cell surface during invasion of host cell, whereas the ___ system of SPI_ is to prevent lysosome fusing with endosome

Back 55

SPI1
Type III injector system, SPI2